1. Field of the Invention
The present invention relates to rolling doors which employ interlocking, pivoting slats and particularly to an improved slat design for use in such doors which provides the capability to improve the thermal insulation and/or acoustical insulation and absorption properties of the door.
2. Description of the Related Art
U.S. Pat. No. 4,436,136, issued to Downey, Jr., and assigned to the owner of the present invention, discloses an insulated slat for use in a curtain of a rolling steel door, a plurality of these slats forming the curtain and improving the insulative characteristics of the door. This patent is hereby incorporated by reference. The slats in the aforenoted Downey patent employ a vinyl backer slat which holds an insulative material in place at the back of the primary or outer slat. In larger door sizes, this vinyl backer slat suffers from the disadvantage that, when the door is coiled, the vinyl backing of the inner wraps and the insulation held therein may be crushed by the weight of the outer wraps in the coil.
Other slat configurations are known and used in the industry to improve the thermal insulative properties of rolling doors. In some instances, metal backer slats have been employed in order to provide stronger reinforcement at the back side of the slat, however, it is recognized in the art that when metal is used for both the outer curtain slats and their associated backer slats, a solid conduction path from one side of the curtain to the other is provided which detracts from the insulative properties of the door. U.S. Pat. No. 4,368,772 issued to Bouthillier discloses one attempt to improve insulation properties of doors employing metal slats by providing a break in the solid conduction path between the outer and inner metal skins of the sectional door by crimping an insulative material between the metal skins at the point where the skins are joined. Notwithstanding such arrangements which provide a break in the solid conduction path of metal slats, curtains employing vinyl backer slats consistently outperform those having metal backer slats from a thermal insulation standpoint.
The insulative properties of a curtain used in a rolling door are also adversely affected by the amount of air allowed to infiltrate through the joints between the slats wherein an upper bead or curved portion from one slat is interlocked with a lower bead or curved portion of a slat immediately thereabove. Designs have been employed to reduce the air infiltration in slats of this type, including the provision of a gasket seal extending across the length of the slat on an upwardly facing surface of the outer slat. An attendant disadvantage of this design is that the gasket is housed in a recess which faces in a concave upward manner, with the gasket and recess forming an undesirable water trap or collection point for water running down the curtain.
The prior art, in addition to lacking fully satisfactory solutions for improving the thermal insulation properties of curtains employing interlocking slats, also is found to be lacking in providing slat designs which provide desired acoustical characteristics. Various applications exist which may require either reduction of sound transmission or enhancement of sound absorption at a door opening.
It is therefore an important object of the present invention to provide a slat assembly configuration which is capable of being used in curtains of the interlocking slat type having improved thermal insulation characteristics.
It is a further object of the present invention to provide a slat assembly configuration which may be used in a curtain made up of interlocking slats wherein the curtain possesses improved acoustical transmission or absorption characteristics, as required, in a particular service.
It is another object of the present invention to provide a slat for use in a curtain made up of interlocking slats wherein the curtain provides a barrier to smoke infiltration under elevated temperature conditions which would be experienced in fires.
It is another object of the present invention to provide a curtain and a rolling door assembly employing curtain having improved thermal and/or acoustical insulative properties.